Carbon nanotubes produced by arc discharge between graphite rods were first discovered and reported in an article by Sumio Iijima entitled “Helical Microtubules of Graphitic Carbon” (Nature, Vol. 354, Nov. 7, 1991, pp. 56-58).
Carbon nanotubes are electrically conductive along their length, are chemically stable, and each can have a very small diameter (much less than 100 nanometers) and large aspect ratios (length/diameter). Due to these and other properties, it has been suggested that carbon nanotubes can play an important role in fields such as microscopic electronics, field emission devices, thermal interface materials, etc.
Nowadays, methods for manufacturing a field emission element using carbon nanotubes typically include mechanical methods and in-situ growth methods.
Mechanical methods mainly involve fixing carbon nanotubes onto a base with chemical agglutinant using a robot arm. Such a mechanical means is time consuming and difficult to operate. Furthermore, it is impossible to manipulate the carbon nanotubes with a diameter smaller than about 1 nanometer.
The in-situ growth method is generally performed as follows. Firstly, a catalyst film is deposited on a base. Secondly, a carbon nanotubes array is grown on the base using a chemical vapor deposition process or an arc-discharge process. However, a binding force between the carbon nanotubes array and the base is weak so that the carbon nanotubes array may easily fall away from the base or be pulled out by an electrical-field force.
What is needed, therefore, is a field emission element with firmly fixed carbon nanotubes and an easy-to-operate method for manufacturing the same.